KM44C256AP-12.

It's a 'DRAM, 1 Mbit, 4-Bit, Fast Page Mode' by Samsung.

It's organized as 256K*4 bit and the speed should be 120 ns according
to the '-12'.

Pinout should be:
 dq1  1   20 Vss
 dq2  2   19 dq4
 /we  3   18 dq3
/ras  4   17 /cas
  nc  5   16 /oe
  a0  6   15 a8
  a1  7   14 a7
  a2  8   13 a6
  a3  9   12 a5
 Vcc 10   11 a4